Leading article: Ten years on, the shame of Guantanamo remains

Exactly four months ago, America and the world commemorated the 10th anniversary of the deadliest and most spectacular terrorist attack in history. Today marks a related and, in some respects, no less sombre 10th anniversary – that of the entry into business of the now infamous prison for terrorist suspects at Guantanamo Bay.

On 11 January 2002, the first batch of 20 captives, picked up on the battlefields of Afghanistan, arrived at the detention centre on the US naval base on the island of Cuba, shackled, hooded and clad in orange jumpsuits. Initially, to a country still traumatised by the 9/11 attacks, the camp seemed a masterstroke. It was unequivocally American territory, yet safely distant from the mainland and, therefore, the George W Bush administration claimed, beyond the reach of the US Constitution and the safeguards contained therein. A perfect place, in other words, to lock away "illegal combatants" not protected by the usual rules of war.

After all, were not these captives "the worst of the worst", in the words of the then Chairman of the Joint Chiefs of Staff? Were they not men so dangerous and desperate that, General Richard Myers maintained, they would "chew through a hydraulics cable to bring a C-17 [transport plane] down?" Ten years on, such sentiments have never seemed as foolish. Far from being a masterstroke, Guantanamo Bay has proved an unmitigated disaster, unnecessary in its own right and an enduring blot on the good name of a superpower that claims to be a beacon for liberty, justice and human rights.

At its peak, Guantanamo held some 500 individuals. In all, 775 prisoners have passed through, most of whom have either been released or sent back to their home countries. Only a tiny handful have actually been tried and convicted. Much may have changed since 2002: the outdoor cages and bleak interrogation huts that greeted the first arrivals have been replaced by a purpose-built prison. Conditions have undoubtedly improved from the early years, when detainees were abused. Legal protection has also improved: in 2008, the Supreme Court ruled that inmates should be accorded the protection of the US Constitution.

But flagrant injustices remain. Of the 171 prisoners who are still at Guantanamo, a relatively small number – such as Khalid Sheikh Mohammed and others accused of organising the September 11 attacks – can genuinely be counted "the worst of the worst". The rest are small fry, many of them innocent of any crime: some simply sold to US troops for bounty, others guilty of nothing more than being in the wrong place at the wrong time. Yet they remain in a legal limbo that has spurred despair and hundreds of suicide attempts, at least four of them successful. Shaker Aamer, the last British resident still being held at the prison, has been there for a decade but has never even been charged. According to his lawyer, Mr Aamer is "falling apart at the seams".

By his second term, even President Bush had concluded that the damage to America's global standing far outweighed any good Guantanamo might be doing, and that the prison should be closed – but nothing happened. Barack Obama went even further. First, he vowed to shut the facility within a year of taking office, by January 2009. A year later, he proposed to transfer the detainees to an unused federal prison in Illinois. Again, to no avail. In the past year, not a single inmate has been released.

The culprit for this shameful state of affairs? Congress. In an all-too-rare display of bipartisanship on Capitol Hill, Republicans and Democrats have combined to block every initiative from the White House to deal with Guantanamo. Faced with such intransigence, Mr Obama can do nothing – and the canker rotting away at America's reputation endures.